The CERVICAL SPINE

Imaging the Traumatized Patient

MI Zucker, MD

A dr Z Lecture

…on imaging cervical spine trauma.

With much gratitude to Jack Harris, MD.

Michael I. Zucker, MD

Professor, Dept. of Radiology

Faculty, Dept. of Emergency Medicine

UCLA Medical Center, David Geffen School of Medicine at UCLA

10,000 spinal cord injuries per year in USA

• Two-thirds are cervical cord.

• The monetary, physical and emotional losses are great.

• Our goal: Early detection of injuries to prevent or decrease neurological and mechanical damage to the spinal column.

STABILITY: A Word or Two

• We talk about it, but what is it?

• A useful definition: An injury is STABLE if putting the spinal column through normal range of motion does not increase neurological or mechanical deficits.

Three Column Theory of Denis

• Spinal column divided into an ANTERIOR, MIDDLE and POSTERIOR column.

• Injury to one column is stable, two or three are unstable.

ANTERIOR COLUMN

• The anterior longitudinal ligament, anterior 2/3 of the body and disc.

MIDDLE COLUMN

• Posterior longitudinal ligament and posterior 1/3 of body and disc.

POSTERIOR COLUMN

• The posterior osseous arch and ligaments.

DOES IT WORK?

If two or three columns injured, lesion is unstable: Works well for C3 to T1.

Does not work so well for C1-2, so consider most or all injuries here unstable.

HOW DO YOU IMAGE THE CERVICAL SPINE?

Plain films?

CT?

MRI?

A combination of modalities?

Is there a consensus?

NO

(But we’re headed toward one)

My Opinion:

• O*pin*ion: A belief held with confidence, but not substantiated by proof.

Imaging Minor Trauma

• LATERAL view from skull base through at least the top one-half of T1. May need to supplement with Swimmer’s view.

• Anterior-posterior (AP)

• Open Mouth Odontoid (OMO)

• If patient is not in cervical collar: Adding Oblique views is an option.

MINOR TRAUMA: Views

Imaging Major Blunt Trauma

• Cross-table LATERAL plain film in Trauma Suite.

• CT entire cervical spine.

• MRI also in selected cases.

• If you wish, AP, OMO, and Swimmer’s views also -- IF they DO NOT cause delay.

• CT: Axial sections base of skull through T1- AND- Sagittal (like a lateral) and Coronal (like AP and OMO) reformatting.

MAJOR TRAUMA: Imaging

• Cross-table Lateral in Trauma Suite

• CT Base of skull through T1

Swimmer’s View in Major Trauma

• A SUPPLEMENTARY view to see C7-T1 in lateral projection. NOT a substitute for a bad lateral. One arm must be elevated, so THEORETICALLY could worsen a mechanical or neurological injury.

• A state-of-the-art CT sagittal reformat is preferable: don’t need to move patient and imaging easier and better.

CT

• Axial sections from base of skull through T1.

• ALWAYS do the ENTIRE cervical spine.

• DON’T do selective imaging with modern scanners.

CT: Sagittal Reformatting

• Reconstructed by computer from axial data: no additional imaging needed.

• Outstanding “lateral/swimmer’s” imaging.

CT: Coronal Reformatting

• Excellent “OMO”

• Excellent “AP”

MRI

• Gold standard for cord, thecal sac, nerve root and disc injuries.

• Very good for ligament injuries.

• Fairly good for fractures, but does miss some. CT much better.

NEUROLOGIC DEFICIT

In my view, ANY neurologic deficit, extant or transient, is MAJOR

trauma, and will need CT followed by MRI.

Any abnormality on Plain Filmsor worrisome examination:

do CT!

Remember: Fractures often come in 2’s and 3’s. The more serious injury

may be the one that is occult.

ARE THERE RISKS?

• Ionizing radiation can damage cells. Younger people are more susceptible than older people. Their cells are more sensitive and they have longer to manifest somatic or genetic damage.

• The radiation dose is significantly higher in CT than in plain films.

• As in most decisions in medicine, one must weigh the risks versus the benefits.

My Approach to Success in Image Interpretation

• Know what to order.

• Know what an optimal imaging series is and don’t accept less.

• Read by check list.

• Know the common lesions.

• Know the commonly MISSED lesions.

Remember: The lesions are the SAME regardless of the imaging

modality

Plain films are still the most common modality.

If you learn on them, you can translate your knowledge to CT and

MRI.

PLAIN FILM Series

• LATERAL

• ANTERIOR-POSTERIOR (AP)

• OPEN MOUTH ODONTOID (OMO)

• *REVERSE WATERS

• *SWIMMER’S

• *OBLIQUES

THE CHECK LIST

View by view

LATERAL view

• This is your MAIN view where 90% of injuries are detected.

• You MUST see T1. If not seen, do Swimmer’s view, unless not safe to do so.

• You did lateral and Swimmer’s and still no luck? DON’T QUIT: DO CT! Once you start an exam you must complete it.

LATERAL View: First Survey

• Look for gross fracture or dislocation.

• Count vertebrae.• Look at skull, entire

airway and adjacent soft tissues.

LATERAL View: Prevertebral Soft Tissues

• Contour is more important than measurements: straight or concave anteriorly, except at larynx.

• Top normal limits: C2 6mm; C6 22mm for adult, 14mm for young child.

LATERAL View: Alignment

• Anterior body line.• Posterior body line.• Spino-laminar line

(called posterior cervical line at C1-3).

LATERAL View: Alignment

• Turning the lateral view HORIZONTALLY can help detect subtle malalignment.

LATERAL View: Spaces

• Disc spaces: too wide, too narrow, not uniform?

• Facet joints: too wide, not uniform?

• Interspinous distances: too wide, too narrow, not uniform?

LATERAL View: C1 and C2

• Basion-dens distance: average 8mm, top normal 12mm.

• C1: Anterior and posterior arch.

• C2: Dens, Harris’ ring, body especially ant/inf corner, pars and posterior arch.

LATERAL VIEW: Predental Space

• In an adult, upper normal is 2.5mm. Space is parallel or narrow “V” shape.

• In a young child, upper normal is 4.5mm.

LATERAL VIEW: Predental Space

LATERAL View: C3-T1

• Body: loss of straight or concave anterior contour, loss of height?

• Posterior arch: subtle cortical irregularity, overt fracture line?

LATERAL VIEW: Child

• Vertebral bodies are bullet shaped.

• Physiologic pseudosubluxations are common, especially C2-4.

• Predental space is wider.

• Lymphoid tissue makes soft tissues more prominent.

SWIMMER’S View

• A supplemental view to see C7-T1.

• Must raise one arm. Probably not a good idea if neurologic deficit, altered level of consciousness, upper arm injury. Could worsen an injury.

ANTERIOR-POSTERIOR View

• Look at first few ribs, sterno-clavicle junction, lung apices.

• Contour of lateral margins of lateral masses.

• Uncovertebral joints.

• Alignment and contour of spinous processes.

• Position and contour of trachea.

The ODONTOID Views

• Open Mouth Odontoid (OMO) is main view.

• Reverse Waters view is supplementary, to see top half of dens ONLY.

OMO

C1-2 lateral mass alignment of lateral margins.

Dens: cortical margin irregularities, fracture lines, tilt.

Upper body of C2 for fracture lines.

Mach lines can be confusing.

The INJURIES

• C1 and C2: by anatomic location

• C3 to T1: by mechanism of injury

(Modified from the classification of John Harris, et al.)

The Atlas and the Axis

• C1 and C2 injuries differ from the rest of the cervical spine and are considered separately.

• Although controversial, best to consider ALL C1 and C2 injuries as UNSTABLE in the acute trauma setting.

Occipital-atlantic Injuries

• Occipital condyle fractures: lateral bending, uncommon, seen only on CT.

• Occipital-atlantic dissociation (OAD): rare distraction injury, usually fatal. Basion-dens distance is abnormal, 12+mm.

The ATLAS: C1

• Anterior arch fracture: extension, uncommon.

• Posterior arch fracture: extension, more common.

• JEFFERSON fracture: axial load, common

C1: Isolated Arch Fractures

• Anterior arch• Posterior arch• CAUTION: You may

be dealing with a Jefferson fracture with occult components: Best to CT all C1 fractures.

JEFFERSON Fracture: C1

• Axial load (“burst”) injury

• Pure (4) or variant (2 or 3) fractures, involving both ant. & post. arches of C1

• Cord injury in 15%

• Lateral view: anterior and posterior arch fractures

• OMO view: lateral displacement of C1 lateral masses

JEFFERSON Fracture: C1

• The lateral masses of C1 and C2 must be aligned on the OMO view.

• 1-2mm of lateral displacement on one side and an EQUAL medial displacement on the other is head rotation.

• ANY other pattern: lateral displacement on both sides or lateral on one side, and none on the other is abnormal.

JEFFERSON FractureCT

• Classical Jefferson: 4 fractures, 2 ant./2 post.

• Jefferson variants: 2 or 3 fractures, but at least 1 ant. & 1 post.

The AXIS: C2

• Dens fractures• Pars fractures• Extension teardrop

fractures

DENS Fractures

• Type I: alar ligament avulsion of the tip; rare.

• Type II: the dens excluding the tip; 2/3.

• Type III: high C2 body; 1/3.

Mechanism of Type II and III is controversial.

TYPE II Dens Fracture

• Interrupted cortical margin, lucent fracture line, tilt especially anterior

• Cord injury in 15%• Delayed or non-union

50+%

TYPE II Dens Fracture

• CT axial

TYPE III Dens Fracture

• Interrupted Harris ring, fat C2, lucent fracture line, tilt especially ant.

• Cord injury in 15%• Heals well.

C2: PARS Fracture

• Called Hangman’s or pedicle fracture, both wrong.

• Extension injury.• Cord injury in 15%.• Non-displaced,

displaced, subluxed.

C2: Extension Teardrop Fracture

• Avulsion by the anterior longitudinal ligament of the anterior-inferior corner of the body.

• Extension mechanism.• Cord injury is low.

C3 to T1

These levels are so similar they will be considered as a unit.

The injuries are grouped by mechanism into “families”.

The “FAMILIES”

Flexion

Flexion-rotation

Extension

Axial loading

“FAMILY FLEXION”Motto: “Anterior impaction,

posterior distraction.”

Family members:– Wedge compression fracture– Hyperflexion sprain– Bilateral interfacetal dislocation– Hyperflexion teardrop fracture-dislocation– Spinous process fracture

Wedge Compression Fracture

• Anterior-superior margin of the body is fractured.

• If loss of height less than 50%, one column injury and so stable.

• If height loss greater than 50%, posterior ligaments presumed torn and so 3 column unstable injury.

• If 3 bodies fractured, unstable even if less than 50% height loss each.

Hyperflexion Sprain

• Tear of the posterior (stable), posterior/ middle (unstable) and posterior/ middle/ anterior (unstable) ligaments without fracture.

• One column stable, 2 or 3 unstable.

• Delay in healing with eventual surgical fusion fairly common.

• Can be a difficult diagnosis.

Flexion-Extension Films

• May be helpful in ligament injuries

-but are-

• Frequently useless due to muscle spasm

Flexion-Extension films

• Rules: Patient must be alert, awake, not intoxicated, able to sit or stand, able to understand commands, and without neurologic deficit.

It is an Active, patient-generated STRESS TEST

• NEVER “help” the patient to “improve” ROM.

• NEVER do passive ROM: this is a neurosurgical procedure done under fluoroscopic control and is controversial.

MRI

• Gold Standard for spinal canal, cord, disc lesions.

• Silver Standard for ligament injuries, but there is no Gold and much better than plain films, CT, and flexion/extension.

Bilateral Interfacetal Dislocation

• BID, also called “locked facets” is anything but locked. It is a severe 3 column injury that is completely unstable.

• Cord is injured in 2/3.

• Body is subluxed anteriorly at least 50%.

• Marked posterior distraction.

Hyperflexion Teardrop Fracture- dislocation

• Among the worst survivable injuries, with nearly 100% severe cord lesion.

• Completely unstable.• Little chance of

neurologic improvement.

Hyperflexion Teardrop Fracture-dislocation

• CT Sagittal Reformat

Spinous Process Fracture

• The “clay shoveler’s fracture”.

• Usually flexion, but can be extension or direct blow.

• Stable if isolated, but do CT to look for associated posterior arch fractures.

Spinous Process Fracture

• CT Sagittal Reformat

FLEXION-ROTATIONInjuries

Unilateral Interfacetal Dislocation and Fracture-dislocation

Unilateral Interfacetal Dislocation

• UID is not stable, as the contralateral capsule ligaments are torn.

• Cord injury is uncommon, but root injury is common, and HNP also occurs.

• Findings can be subtle: less than 50% subluxation, malalignment of spinous processes.

CT: This is a normal facet joint, normal “hamburger sign”

UID

• CT: UID has “reversed hamburger sign” of facet joint.

• CT is also more sensitive for associated lateral mass fractures.

UID

• Oblique view

• CT Sagittal Reformat

EXTENSION InjuriesFamily motto: “Anterior

distraction, posterior impaction.”

Posterior arch fractures

Extension teardrop fractures

Extension fracture-dislocations

Posterior Arch Fractures• Plain films are insensitive, CT

is outstanding.• Isolated: pedicle, lateral mass,

lamina or spinous process.• Multiple fractures are common.

Pedicle/lamina fractures cause free-floating lateral mass.

• May be additional element of lateral bending.

• Stability depends on what is fractured.

Extension Teardrop Fracture

• Avulsion fracture caused by anterior longitudinal ligament.

• Vertical narrow fracture of anterior-inferior corner of body.

• Most common site is C2.

• Unstable.

EXTENSION Fracture- dislocation

• More severe force fractures the body along end plate and causes subluxation, usually posterior.

• Fracture is oriented longitudinally, and there is malalignment of the bodies.

AXIAL Loading

• “Burst” fractures explode the body.

• All are very unstable and cause cord injury in 2/3 (except C1).

• There is usually an element of flexion also.

BURST Fractures

On lateral, body is compressed anteriorly, inferior end plate often fractured, posterior body contour is convex.

On AP, body fracture is vertical or oblique and pedicles spread.

BURST Fractures

• CT more accurately displays the fracture pattern and the very important degree of narrowing of the spinal canal.

REMEMBER:

CT is much more sensitive for fractures than plain films.

MRI is the standard for soft tissue injuries.

GOODBYE AND GOOD IMAGING!

• Copyright 2004• M. I. Zucker